Grey's Anatomy, Season 3

Meredith:
[voiceover] A patient's history is as important as their symptoms. It's what helps us decide if heartburn's a heart attack... if a head ache's a tumor. Sometimes patients will try to re-write their own histories. They'll claim they don't smoke, or forget to mention certain drugs... which in surgery can be the kiss of death. We can ignore it all we want, but our history eventually always comes back to haunt us.